Let's talk about gerunds. Let me start by defining that a 'gerund' is a noun, taken from a verb, that ends in -ing. For example:
The village assembled to watch the hanging.

A gerund can also be plural:
Since the criminal had an accomplice, there were actually two hangings.

Here's an interesting point: in the case of
"People like to talk about celebrities' private lives rather than their acting."
we naturally say "acting" instead of "actings". It's definitely proper English... but I can't think of a straight-out explanation as to why.

It might take one post to answer the question, but it could easily be a hard concept for a person studying English to learn, so I want to get an answer from you guys (and start a related discussion).

It's too simplistic to say that a gerund is a noun. It IS nominalized, so it can function LIKE a noun, but it isn't one. I think most gerunds CANNOT be made plural, and the irregularity lies with the "hangings".

I believe "hanging" can only be made plural because the term has become a noun in its own right, and does not necessarily refer to a man being hanged, but broader in scope to include the entire event/affair, the gathering crowd, reading of the crimes, and so forth.

Other gerunds, not having acquired this "true noun" status are treated as they should be.

I think in terms of the word acting I would say that you don't split someone's acting up into their different movies when you imagine the person acting. Rather you think of their career as a whole and perhaps this is the reason why people say acting rather than actings?

This is probably the case with a lot of verbs changed to gerunds however i realised one doesn't conform.

I might say "Jack Cooper has caused many deaths with his shootings"

you wouldn't say shooting. Aha so yes as someone said - if it's an event then more often than not there will be an S but if it's an ongoing/recently completed action there won't.

In some of the subforums, like this one, there are so few posts that there are 2 year old posts on the first page of the subforum. I think that's what accounts for a number of the necroposts, so it's not really the new poster's fault.

I personally don't mind, but I did spend time and effort creating a reply to try and help a poster who had already been satisfied with their answer 2 years ago, all because I was led to believe this was a new thread.

1.5: Old threads can and should only be revived if the post benefits the community (Posts like "oh, thanks. lol. I see." etc... aren't beneficial). So unless your post is bringing up important information, or asking for better clarification, then we request you refrain from posting in old threads

If you disagree about whether it's a good post, then comment on that. But personally I would rather see folks drop the compulsion to criticize the necromancy of a post.